Computer program, method, and apparatus for determining a plurality of functional ocular parameters

Abstract

The invention relates to a computer program that when executed on a computer causes a system to execute a method, particularly a computer-implemented method for determining a plurality of functional ocular parameters, with the system comprising an optical system ( 3 ) with a display system ( 4 ) that is configured to independently project a visual stimulus to a left and a right eye of a test person, an eye-tracking system ( 5 ) configured to record a gaze direction ( 100 ) and a pupil size ( 102 ) of the left as well as the right eye, said computer ( 2 ) being configured to control the optical system ( 3 ) and to receive recorded data from the eye-tracking system ( 5 ), wherein an afferent pupillary defect (APD), particularly a relative afferent pupillary defect (RAPD) is determined from a first trial session consisting of a sequence of first kind of stimuli presented to the left and the right eye of the test person eyes with the display system ( 4 ), and wherein a visual field ( 400 ) is determined from a second trial session consisting of a sequence of second kind of stimuli presented to the left and the right eye of the test person with the display system ( 4 ), wherein from the first and/or the second trial session a strabismus is determined as well, by determining one or more strabismus angles.

1 . A computer program that when executed on a computer causes a system to execute a method for determining a plurality of functional ocular parameters, wherein the system comprises an optical system ( 3 ) with a display system ( 4 ) that is configured to independently project a visual stimulus to a left and a right eye of a test person, an eye-tracking system ( 5 ) configured to record a gaze direction ( 100 ) and a pupil size ( 102 ) of the left as well as the right eye, said computer ( 2 ) being configured to control the optical system ( 3 ) and to receive recorded data from the eye-tracking system ( 5 ),
 wherein an afferent pupillary defect (APD), particularly a relative afferent pupillary defect (RAPD) is determined from a first trial session consisting of a sequence of first kind of stimuli presented to the left and the right eye of the test person eyes with the display system ( 4 ), and   wherein a visual field ( 400 ) is determined from a second trial session consisting of a sequence of second kind of stimuli presented to the left and the right eye of the test person with the display system ( 4 ), wherein from the first and/or the second trial session a strabismus is determined as well, by determining one or more strabismus angles.   
     
     
         2 . The computer program according to  claim 1 , wherein executing the first trial session comprises the steps of:
 Recording data comprising information on the pupil size ( 102 ) and the gaze direction ( 100 ) during the first trial session;   Determining from the recorded data of the first trial session the APD by analyzing with the computer ( 2 ) a temporal course ( 103 ) of the pupil sizes ( 102 ) of the left and the right eye;   Determining from the recorded gaze directions ( 100 ) of the first trial session the one or more strabismus angles by analyzing with the computer ( 2 ) a size and a direction of saccadic eye movements ( 101 ).   
     
     
         3 . The computer program according to  claim 1 , wherein executing the second trial session comprises the steps of:
 Recording data comprising information on the gaze direction ( 100 ) of the test person;   Determining from the recorded gaze directions ( 100 ) of the second trial session the visual field ( 400 ) and the one or more strabismus angles by analyzing with the computer ( 2 ) saccadic eye movements of the test person.   
     
     
         4 . The computer program according to  claim 1 , wherein each visual stimulus of the first kind of visual stimuli comprises a fixation object ( 11 ) that is displayed on the display system ( 4 ) at a display location of the display system ( 4 ), wherein the fixation object ( 11 ) is a spatially confined graphical object that allows fixation of an eye on the fixation object ( 11 ). 
     
     
         5 . The computer program according to  claim 4 , wherein the first kind of visual stimuli are displayed alternatingly and repeatedly to the right and the left eye, wherein the pupil size ( 102 ) and the gaze direction ( 100 ) are recorded for both eyes, particularly at a frame rate of at least 100 Hz. 
     
     
         6 . The computer program according to  claim 5 , wherein the first trial session comprises a plurality of gaze direction blocks, wherein in each gaze direction block the first kind of visual stimulus is repeatedly and alternatingly presented to right and the left eye, wherein the fixation object is displayed at different display locations for different gaze direction blocks, particularly, wherein for each gaze direction block the APD and/or RAPD is determined as well. 
     
     
         7 . The computer program according to  claim 6 , wherein the fixation object ( 11 ) is displayed at the same display location for the same gaze direction block, wherein the size and the direction of the saccadic eye movement ( 101 ) is determined from the recorded saccadic eye movement each time the first kind of stimulus switches from the left to the right eye or vice versa, particularly wherein the at least one strabismus angle is determined for each gaze direction block, such that the at least one strabismus angle is determined in relation to a gaze direction. 
     
     
         8 . The computer program according to  claim 6 , wherein in each gaze direction block for each eye and for each presented first kind of stimulus, the size and the direction of the saccadic eye movement ( 101 ) is determined, wherein in a subsequent presentation of the first kind of visual stimulus ( 11 ) of the same gaze direction block, the display location of the fixation object is adjusted, such as to compensate the saccadic eye movement ( 101 ) in size and direction as determined from a previously presented first kind of stimulus of the gaze direction block, particularly until the saccadic eye movement ( 101 ) is minimized in the same gaze direction block, particularly wherein the at least one strabismus angle corresponds to the adjusted display location, particularly wherein the at least one strabismus angle is determined for each gaze direction block, such that the strabismus angle is determined in relation to a gaze direction. 
     
     
         9 . The computer program according to  claim 1 , wherein each visual stimulus of the second kind of visual stimuli comprises a luminance object displayed on a uniform background at a relative position on the display system ( 4 ), wherein during the second trial session the luminance object of second kind of visual stimulus is displayed sequentially at a plurality of selected relative positions ( 402 ), wherein the second kind of visual stimuli are displayed alternatingly or sequentially to the right and the left eye, particularly wherein the respective other eye is presented with a neutral stimulus that is identical to the second kind of stimulus without the luminance object, wherein each time the luminance object is displayed at a selected relative position ( 402 ), it is determined, whether the test person has detected the luminance object at the selected relative position ( 402 ), wherein if the test person has detected the luminance object, the luminance object is subsequently displayed at a different selected relative position, wherein the luminance object is displayed at the selected relative position again at a later trial with a decreased luminance, wherein if the test person has not detected the luminance object at the selected relative position, the luminance object is displayed repeatedly at the selected relative position with increasing luminance until the test person has detected the luminance object, such that for each selected relative position a luminance detection threshold for each eye of the test person is determined, such that the visual field ( 400 ) is determined in form of a threshold perimetric measurement. 
     
     
         10 . The computer program according to  claim 9 , wherein the luminance object is deemed detected by the test person, if a saccadic eye movement toward the displayed luminance object is recorded by the eye-tracking system within a first time interval during which the luminance object is displayed and wherein the luminance object stimulus is deemed not detected by the test person if no saccadic eye movement toward the luminance object is recorded by the eye-tracking system within a second time interval that is longer than the first time interval. 
     
     
         11 . The computer program according to  claim 10 , wherein the at least one strabismus angle is determined for the selected relative position ( 402 ) from the saccadic eye movement and in particular from the amplitude and the direction of the saccadic eye movement, when the second kind of stimulus switches from the left to the right eye or from the right to the left eye, and if the luminance object is deemed detected by both eyes, or wherein the at least one strabismus angle is determined for the selected relative position by subtracting the gaze directions of the left and right eye from each other. 
     
     
         12 . The computer program according to  claim 4 , wherein a gaze direction reset routine is performed, wherein said routine comprises the steps of:
 Particularly, determining whether the selected relative display position is located outside of a physical tracking limit of the eye tracking system or a physical display limit of the display system and if yes:   presenting a supra-threshold object, such as the fixation object or the luminance object with a supra-threshold luminance that lies above the luminance detection threshold at a current gaze direction of the eye,   moving the supra-threshold object to a new display location along a trajectory with a predefined horizontal and vertical speed,   particularly, hiding the supra-threshold object;   particularly, performing the method steps of the previous embodiment at the selected relative position that was determined to lie outside of the physical display limit or the physical tracking limit of the eye tracker before the gaze reset routine has been performed.   
     
     
         13 . The computer program according to  claim 12 , wherein during the gaze reset routine, the supra-threshold object moves with a predefined velocity pattern along a horizontal direction and a vertically direction, wherein a deviation between a velocity of the detected eye movement following the supra-threshold object and the velocity pattern of the supra-threshold object is determined for each supra-threshold object movement direction, wherein from the deviation a gain of smooth pursuit eye movement is determined from the gaze reset routine. 
     
     
         14 . The computer program according to  claim 1 , wherein the functional ocular parameters that are determined further comprise
 a fusional amplitude of the test person;   wherein for determining the fusional amplitude, the method further comprises the steps of:   Executing a third trial session, wherein the third trial session comprises a third kind of visual stimuli that are presented with the optical system simultaneously to the left and the right eye of the test person;   Recording data during the third trial session comprising information on the gaze direction;   Determining from the recorded gaze direction of the third trial session at least a fusional amplitude by analyzing with the computer a vergence eye movement of the test person in response to the presented third kind of visual stimuli of the third trial session.   
     
     
         15 . The computer program according to  claim 1 , wherein the functional ocular parameters that are determined further comprise
 a visual acuity of the test person;   wherein for determining the visual acuity, the method further comprises the steps of:   executing a fourth trial session, wherein the fourth trial session comprises a plurality of fourth kind of visual stimuli ( 501 ) that are presented with the optical system ( 4 ) to the left and/or the right eye of the test person;   recording data during the fourth trial session comprising information on the gaze direction;   determining from the recorded data of the fourth trial session at least the visual acuity by analyzing with the computer ( 2 ) a movement of the left and the right eye of the test person in response to the presented fourth kind of visual stimuli of the fourth trial session.   
     
     
         16 . A neuro-ophthalmoscope ( 1 ) comprising an optical system ( 2 ) with a display system ( 4 ) that is configured to independently project a visual stimulus to a left and a right eye of a test person, an eye-tracking system ( 5 ) configured to record a gaze direction and a pupil size of the left as well as the right eye, a computer ( 2 ) configured to control the optical system ( 2 ) and to receive recorded data from the eye-tracking system ( 5 ), as well as program code stored on the computer ( 2 ) to execute the method according to  claim 1 , particularly, wherein the optical system ( 2 ) and the eye-tracking system ( 5 ) is comprised in a near-eye display, such as in VR-goggles, wherein the near-eye display further comprises for each eye a lens assembly ( 6 ) that is adjustable such that optical aberrations of each eye of a test person may be compensated by the lens assembly ( 6 ). 
     
     
         17 . The computer program according to  claim 9 , wherein a gaze direction reset routine is performed, wherein said routine comprises the steps of:
 determining whether the selected relative display position is located outside of a physical tracking limit of the eye tracking system or a physical display limit of the display system and if yes:   presenting a supra-threshold object, such as the fixation object or the luminance object with a supra-threshold luminance that lies above the luminance detection threshold at a current gaze direction of the eye,   moving the supra-threshold object to a new display location along a trajectory with a predefined horizontal and vertical speed,   hiding the supra-threshold object;   performing the method steps of the previous embodiment at the selected relative position that was determined to lie outside of the physical display limit or the physical tracking limit of the eye tracker before the gaze reset routine has been performed.